Mother Plants w/Several Issues - Additional Opinions Requested

Hello and Happy Thanksgiving Eve ...

I have (2) mother plants which are no longer looking healthy since their nutrient solution was changed about 10 days ago. I did look at several diagnosis guides provided on this forum and have some thoughts about what the problem is, but since this is my first time giving this a go, I would appreciate additional opinions! What is the cause (or causes) of the problems shown in the picture and what is a recommended fix?

Background Info:

• Indoor grow (tent)
• Tops of plants are about 9 inches away from light
• Light is set at 420 Watts (har-dee-har-har )
• Rockwool Cube Medium
• Growth Stage - Veg (mother plants)
• Successfully changed out nutrient solution several other times with no immediate issues
• This time, I used distilled water instead of hard water (hard water has always been used in the past)
• Used the same amount of nutrients (micro, bloom & grow)
• Tent temperature: 76 °F
• Nutrient solution temperature: 69 °F
• Relative humidity in tent (partially open to keep temps down): 26%
• PPM of nutrient solution: 442
• pH of nutrient solution: 6

Problems:

• Bottom leaves are dying and falling off
• Most leaf tips have turned brown and are curling straight up
• Some leaves have their edges turning yellow
• A few leaves have some strange dark colored splotches on them

Thank you in advance for reading this!!

You took away their cal/mag source when you switched water.

Bugeye said:

You took away their cal/mag source when you switched water.

Click to expand...

Thanks! I'm going to add some now; you had actually helped me with a previous problem and recommended cal/mag for that, so I already have some on hand!